While pushbutton switches with magnetically coupled armatures already have many applications, cost per switch is higher than many membrane switches. The major expenses of a magnetically coupled pushbutton switch are the cost of stamping and plating armatures and the cost of aligning and adhering the numerous switch layers. A major selling point of a magnetically coupled pushbutton switch is long life, but in our disposable society that is not of great interest to many manufacturers. The present invention is a magnetically coupled pushbutton switch that is flexible, is inexpensive to make, and has no small piece parts that need to be individually aligned.
Magnetically coupled switches of the prior art, exemplified in FIGS. 1-4, normally have an electrically conductive armature 2 that is magnetically held by a coupler magnet layer 4 in a rest position, as in FIG. 1, spaced from switch contacts 6 on a non-conductive substrate layer 8. A user-provided actuation force applied to a crown 10 of the electrically conductive armature (usually stamped sheet metal that is silver plated) causes it to snap free of the coupler magnet layer and close the switch contacts by electrically connecting them. Withdrawal of the actuation force allows the coupler magnet layer to attract the electrically conductive armature back to the rest position, resulting in a reopening of the switch. A non-conductive spacer layer 12 (such as high density foam) is adhesively fixed to the substrate layer, with a cavity 14 in the spacer layer exposing the switch contacts. The coupler magnet layer overlies the spacer layer. The electrically conductive armature is magnetically coupled to the bottom of the coupler magnet layer so that the electrically conductive armature is housed within the cavity in the spacer layer. The armature's crown protrudes through an aperture 16 in the coupler magnet layer. Typically, a polyester membrane layer 18 with suitable graphics overlies the coupler magnet layer to seal the switch and to direct a user of the switch as to location and function of the switch.
Magnetically coupled pushbutton switches of the prior art, as shown and described in U.S. Pat. Nos. 5,523,730, 5,990,772, 6,262,646, and 6,556,112, incorporated herein by reference but not limitation, all have an electrically conductive armature piece-part that can travel through a unique pivot/click (FIG. 2/FIG. 3) movement designed to create a very distinct tactile feedback to a switch user. FIG. 2 shows that application of an actuation force 20 causes a heel 22 of the electrically conductive armature to break away from the coupler magnet layer 4 and travel to the substrate layer 8 where in the heel stops (creating a first tactile feedback) and functions as a fulcrum for the electrically conductive armature. FIG. 3 shows that continued application of the actuation force causes a toe 26 of the electrically conductive armature to abruptly break away from the coupler magnet layer so that the toe contacts the substrate layer (creating a second tactile feedback). The exploded view in FIG. 4 shows five layers. An additional four layers of adhesive are needed to hold the assembly together. Some of the assemblies described in the prior art have as many as thirteen layers, including adhesive layers. The armatures shown in FIG. 4 must be individually aligned and placed so that the crowns 10 properly seat within the apertures 16. There is a great need to eliminate switch layers and adhesive layers, as well as a need to simplify alignment of armatures.
Alternatively, the momentary contact magnetic switches shown and described in U.S. Pat. No. 4,513,271 have a flexible magnet armature that breaks away from a steel faceplate to create two distinct switch functions. Such an armature design could be combined with the magnetically coupled pushbutton switch assembly described above, but there would still be a substantial cost to align/position the armatures, which are small magnets that will stick to every magnetic material they contact, such as other small magnets. Additionally, there would still be a need for adhesive layers, a foam spacer layer, and the projections shown and described in U.S. Pat. No. 4,513,271 would need to be used because sheet magnet armatures crack and break when there is an attempt to stamp a crown into the sheet magnet.